CHMP1A Summary

CHMP1A (Charged multivesicular body protein 1a) is a peripherally associated component of the ESCRT-III complex involved in multivesicular body (MVB) formation and endosomal cargo sorting (UniProt: Q9HD42). The protein mediates vesicle extrusion and membrane fission activities required for lysosomal protein degradation, cytokinesis, and enveloped virus budding, and plays roles in chromosome condensation and Polycomb group gene silencing.

CHMP1A is expressed across tissues involved in membrane trafficking and cell division. UniProt documents an association with Pontocerebellar hypoplasia 8 (PCH8; MIM 614961), an autosomal recessive neurodevelopmental disorder featuring severe psychomotor retardation, hypotonia, spasticity, and pontocerebellar hypoplasia.

In Alzheimer's Disease, CHMP1A shows ambiguous regulation across subcellular fractions in post-mortem AD brain compared to age-matched controls (Chaparral AD proteomics). The mean log2 fold-change is 0.0075, indicating minimal net change overall, though direction varies between the two fractions examined in the TMT-labeled quantitative proteomics experiment. This suggests CHMP1A's role in endosomal-lysosomal trafficking may be compartmentally dysregulated in AD pathology.